1. Field of the Invention
The present invention relates to a liquid jet recording apparatus, and more particularly to a liquid jet recording apparatus equipped with a recovery device for resolving so-called clogging of the recording head, and a method of recovery.
2. Related Background Art
In a liquid jet recording head in which recording liquid is emitted as a flying droplet from a small discharge port, there may result failure of the liquid emission or distorted flight of liquid droplet due to the trapping of bubbles in a liquid path connected to the discharge port or in a liquid chamber connected to the liquid path, or coagulation of dust or recording liquid around the discharge port, or an increase in the viscosity of the recording liquid. In order to prevent such phenomena, and for the initial filling of recording liquid into the liquid path, a so-called recovery operation has been conducted, for example, after a prolonged interruption of the recording operation.
For conducting a recovery operation there are already known certain devices, such as the one for covering a discharge port surface of the recording head in which discharge ports are formed with a cap member and sucking the internal space under the cap member with a pump and others to extract the recording liquid through the discharge ports by the generated negative pressure together with the dust and bubbles therein as disclosed, for example, in U.S. Pat. Nos. 4,276,554, 4,410,900, 4,600,931, 4,394,669, or the one for forcedly expelling the recording liquid through the discharge ports together with the dust and bubbles therein by means of a pump provided in the liquid supply system to the recording head, as disclosed, for example, in U.S. Pat. Nos. 4,276,554 and 4,590,494.
However, though such conventional devices are capable of filling the recording head with new recording liquid and removing the dust and bubbles from the head by sucking or expelling the recording liquid from the recording head, it is difficult to completely eliminate the recording liquid deposited in the vicinity of discharge ports on the discharge port surface. Such deposited recording liquid bends the flight of the liquid droplet toward the recording liquid, thus deteriorating the image quality of the recording. Also, a careless recovery operation may cause deposition of the extracted liquid in the vicinity of the discharge ports, thus resulting in a problem the same as the remaining recording liquid. For removing such liquid it has been proposed to use a mechanism for wiping off the sticking liquid in addition to the recovery device, as disclosed in U.S. Pat. No. 4,306,245, but such method requires a complicated structure and the recovery device, requiring a pump, cannot be simplified much.